#define JPEG_INTERNALS
#include "jinclude.h"
#include "jpeglib.h"
#include "jdct.h"

typedef struct {
  struct jpeg_inverse_dct pub;	/* public fields */
  int cur_method[MAX_COMPONENTS];
} my_idct_controller;

typedef my_idct_controller * my_idct_ptr;

typedef union {
  ISLOW_MULT_TYPE islow_array[DCTSIZE2];
  #ifdef DCT_IFAST_SUPPORTED
  IFAST_MULT_TYPE ifast_array[DCTSIZE2];
  #endif
  #ifdef DCT_FLOAT_SUPPORTED
  FLOAT_MULT_TYPE float_array[DCTSIZE2];
  #endif
} multiplier_table;

#ifdef DCT_ISLOW_SUPPORTED
#define PROVIDE_ISLOW_TABLES
#else
#ifdef IDCT_SCALING_SUPPORTED
#define PROVIDE_ISLOW_TABLES
#endif
#endif

METHODDEF( void )
start_pass( j_decompress_ptr cinfo ) {
  my_idct_ptr idct = ( my_idct_ptr ) cinfo->idct;
  int ci, i;
  jpeg_component_info *compptr;
  int method = 0;
  inverse_DCT_method_ptr method_ptr = NULL;
  JQUANT_TBL * qtbl;
  for( ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
       ci++, compptr++ ) {
    switch( compptr->DCT_scaled_size ) {
        #ifdef IDCT_SCALING_SUPPORTED
      case 1:
        method_ptr = jpeg_idct_1x1;
        method = JDCT_ISLOW;	/* jidctred uses islow-style table */
        break;
      case 2:
        method_ptr = jpeg_idct_2x2;
        method = JDCT_ISLOW;	/* jidctred uses islow-style table */
        break;
      case 4:
        method_ptr = jpeg_idct_4x4;
        method = JDCT_ISLOW;	/* jidctred uses islow-style table */
        break;
        #endif
      case DCTSIZE:
        switch( cinfo->dct_method ) {
            #ifdef DCT_ISLOW_SUPPORTED
          case JDCT_ISLOW:
            method_ptr = jpeg_idct_islow;
            method = JDCT_ISLOW;
            break;
            #endif
            #ifdef DCT_IFAST_SUPPORTED
          case JDCT_IFAST:
            method_ptr = jpeg_idct_ifast;
            method = JDCT_IFAST;
            break;
            #endif
            #ifdef DCT_FLOAT_SUPPORTED
          case JDCT_FLOAT:
            method_ptr = jpeg_idct_float;
            method = JDCT_FLOAT;
            break;
            #endif
          default:
            ERREXIT( cinfo, JERR_NOT_COMPILED );
            break;
        }
        break;
      default:
        ERREXIT1( cinfo, JERR_BAD_DCTSIZE, compptr->DCT_scaled_size );
        break;
    }
    idct->pub.inverse_DCT[ci] = method_ptr;
    if( ! compptr->component_needed || idct->cur_method[ci] == method )
    { continue; }
    qtbl = compptr->quant_table;
    if( qtbl == NULL )		/* happens if no data yet for component */
    { continue; }
    idct->cur_method[ci] = method;
    switch( method ) {
        #ifdef PROVIDE_ISLOW_TABLES
      case JDCT_ISLOW: {
        ISLOW_MULT_TYPE * ismtbl = ( ISLOW_MULT_TYPE * ) compptr->dct_table;
        for( i = 0; i < DCTSIZE2; i++ ) {
          ismtbl[i] = ( ISLOW_MULT_TYPE ) qtbl->quantval[i];
        }
      }
      break;
      #endif
      #ifdef DCT_IFAST_SUPPORTED
      case JDCT_IFAST: {
        IFAST_MULT_TYPE * ifmtbl = ( IFAST_MULT_TYPE * ) compptr->dct_table;
#define CONST_BITS 14
        static const INT16 aanscales[DCTSIZE2] = {
          /* precomputed values scaled up by 14 bits */
          16384, 22725, 21407, 19266, 16384, 12873,  8867,  4520,
          22725, 31521, 29692, 26722, 22725, 17855, 12299,  6270,
          21407, 29692, 27969, 25172, 21407, 16819, 11585,  5906,
          19266, 26722, 25172, 22654, 19266, 15137, 10426,  5315,
          16384, 22725, 21407, 19266, 16384, 12873,  8867,  4520,
          12873, 17855, 16819, 15137, 12873, 10114,  6967,  3552,
          8867, 12299, 11585, 10426,  8867,  6967,  4799,  2446,
          4520,  6270,  5906,  5315,  4520,  3552,  2446,  1247
        };
        SHIFT_TEMPS
        for( i = 0; i < DCTSIZE2; i++ ) {
          ifmtbl[i] = ( IFAST_MULT_TYPE )
                      DESCALE( MULTIPLY16V16( ( JPEG_INT32 ) qtbl->quantval[i],
                                              ( JPEG_INT32 ) aanscales[i] ),
                               CONST_BITS - IFAST_SCALE_BITS );
        }
      }
      break;
      #endif
      #ifdef DCT_FLOAT_SUPPORTED
      case JDCT_FLOAT: {
        FLOAT_MULT_TYPE * fmtbl = ( FLOAT_MULT_TYPE * ) compptr->dct_table;
        int row, col;
        static const double aanscalefactor[DCTSIZE] = {
          1.0, 1.387039845, 1.306562965, 1.175875602,
          1.0, 0.785694958, 0.541196100, 0.275899379
        };
        i = 0;
        for( row = 0; row < DCTSIZE; row++ ) {
          for( col = 0; col < DCTSIZE; col++ ) {
            fmtbl[i] = ( FLOAT_MULT_TYPE )
                       ( ( double ) qtbl->quantval[i] *
                         aanscalefactor[row] * aanscalefactor[col] );
            i++;
          }
        }
      }
      break;
      #endif
      default:
        ERREXIT( cinfo, JERR_NOT_COMPILED );
        break;
    }
  }
}

void jinit_inverse_dct( j_decompress_ptr cinfo ) {
  my_idct_ptr idct;
  int ci;
  jpeg_component_info *compptr;
  idct = ( my_idct_ptr )
         ( *cinfo->mem->alloc_small )( ( j_common_ptr ) cinfo, JPOOL_IMAGE,
                                       SIZEOF( my_idct_controller ) );
  cinfo->idct = ( struct jpeg_inverse_dct * ) idct;
  idct->pub.start_pass = start_pass;
  for( ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
       ci++, compptr++ ) {
    compptr->dct_table =
      ( *cinfo->mem->alloc_small )( ( j_common_ptr ) cinfo, JPOOL_IMAGE,
                                    SIZEOF( multiplier_table ) );
    MEMZERO( compptr->dct_table, SIZEOF( multiplier_table ) );
    idct->cur_method[ci] = -1;
  }
}
